CDMA communication systems today are vulnerable to interference and cross-talk between mobile stations (MSs) which are assigned the same public long code mask (PLCM). Because PLCMs are intended to provide a unique addressing mechanism for mobiles, this PLCM sharing is unintended but nonetheless present in today's systems. PLCM sharing can occur as a result of hard handoffs. For example, two MSs served by different base stations (BSs) may be assigned the same PLCM by the independent operation of each BS. Interference can occur, then, when one MS hands off to the same cell/sector occupied by the other MS. Since both MSs are using the same PLCM in proximity to each other, the users may hear each others' conversations without realizing that their individual conversations are no longer private.
Although this cross-talk problem has existed in CDMA systems for many months and has received the attention of 3GPP2 standards body participants, the problem persists even in the most recent PLCM-related changes, the so-called “PLCM—32” functionality. The PLCM—32 functionality was introduced into IS-2000 Revision C and 3G-IOSv4.3 (as both exist on Apr. 11, 2003) to decouple the long code mask from the subscriber electronic serial number (ESN). It allows the BS to specify the long code mask during call setup; however, there is no guideline in the generation of the 32-bit PLCM—32 number by a BS. Therefore, the possibility of sharing PLCM—32 numbers generated by different BSs, especially those of different vendors, still exists. Such sharing must be resolved for hard handoff to avoid the cross-talk problem. Thus, a need exists for improved PLCM management during hard handoffs.